Jumperless Aux Battery Bypass

[Pismo61]

Which cable on the negitive side is the negitive for the aux.battery?Once you pull fuse 42 out and disconnect the negitive cable you must press the ess button everytime you start the Jeep,correct?This just takes the aux. battery out of the loop?

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[Bayrat]

Which cable on the negitive side is the negitive for the aux.battery?Once you pull fuse 42 out and disconnect the negitive cable you must press the ess button everytime you start the Jeep,correct?This just takes the aux. battery out of the loop?

That is my question also. Sounds as though all this does is eliminate that problematic battery buried in the bowls of the vehicle but doesn't actually eliminate the SS function, which is the most annoying to me.

 

[Stuckinthesand]

That is my question also. Sounds as though all this does is eliminate that problematic battery buried in the bowls of the vehicle but doesn't actually eliminate the SS function, which is the most annoying to me.

You still need to press the ESS disable button or have some kind of tazer, eliminator etc. The negative cable for the aux battery is on the post closest to the passenger fender. You can see in the OP’s first post the correct cable. As far as I know there is nothing that actually eliminates the ESS. Even the aftermarket dual battery setups just allow easier access to the aux battery. I would recommend disconnecting the aux battery if you do this fuse pull as a bad aux can and most likely will drain your main battery. I would think if you forget to disable ESS here and there it probably wouldn’t be a huge issue as the alternator charges the main battery but I would not suggest doing this on a daily basis.

 

[Jebiruph]

Here's my original post on the aux battery bypass, lot's of information here about what the bypass does. https://www.jlwranglerforums.com/forum/threads/3-6l-ess-aux-battery-bypass.17293/post-423590

 

[TheNewGuy]

Which cable on the negitive side is the negitive for the aux.battery?Once you pull fuse 42 out and disconnect the negitive cable you must press the ess button everytime you start the Jeep,correct?This just takes the aux. battery out of the loop?

Get yourself a SmartStopStart. No more pushing the button every time you start her up.

 

[Bayrat]

The way it is disabled has to disconnect the second battery and bypass the function it serves ie to trip a relay, which allows the main battery to start the vehicle. I believe this is described in the thread which explains how to jumper in the fuse box.

 

[Fudster]

Which cable on the negitive side is the negitive for the aux.battery?Once you pull fuse 42 out and disconnect the negitive cable you must press the ess button everytime you start the Jeep,correct?This just takes the aux. battery out of the loop?

In my testing I temporarily disconnected the negative cable leading from the ESS battery to the main battery's negative post and left it dangling.

I attempted to cold crank the 3.6L and on first attempt it failed.

But on second attempt it succeeded, turning on the ESS off light in the EVIC.

All subsequent cold cranks worked on the first try and this ESS off light remained illuminated until the ESS battery's negative cable was reconnected.

I think this is how most 3.6L JLs work, baring some of the earlier 2018s without TSB 18-092-19.

It seems to be exactly what you want. Just disconnect this cable (NOT the one leading from the negative terminal of the main battery to the body ground: leave that connected) and electric tape the ends of that danglng cable.

Problem solved.

 

[Jebiruph]

Upon further review, this doesn't work to keep the @! error light off. Even though the initial start passes the aux battery test, somehow it figured out something was wrong and turned the error light on.

 

[Stuckinthesand]

Upon further review, this doesn't work to keep the @! error light off. Even though the initial start passes the aux battery test, somehow it figured out something was wrong and turned the error light on.

I will have to check again today but I have had this setup since Saturday and have not had the error yet. I even made sure the remote start still worked when I put the doors back on last night.

 

[Stuckinthesand]

Went out at lunchtime and took a ride. I can confirm no error for me. I’ve been out and about since Saturday when I tried this. I will report back in a few days or if the error comes on.

 

[Jebiruph]

"It looks like meats' back on the table, boys". Upon further further review, it occurred the me that @! error light might be a residual error inadvertently triggered during my experiment. So I started with the intent to clear the error and try again, but what I found was that I left the battery sensor unplugged. Plugged that in and tested- fuse out, aux ground disconnect and no error light.

Sorry for the emotional roller coaster.

On a related note, I couldn't get Jscan to show the error condition, but AlfaODB found it. It wasn't an error code, more of an error condition.

 

[TheNewGuy]

"It looks like meats' back on the table, boys". Upon further further review, it occurred the me that @! error light might be a residual error inadvertently triggered during my experiment. So I started with the intent to clear the error and try again, but what I found was that I left the battery sensor unplugged. Plugged that in and tested- fuse out, aux ground disconnect and no error light.

Sorry for the emotional roller coaster.

On a related note, I couldn't get Jscan to show the error condition, but AlfaODB found it. It wasn't an error code, more of an error condition.

By battery sensor you mean IBS?

 

[Jebiruph]

By battery sensor you mean IBS?

Yes

 

[bohnster]

Thanks for pushing though on this. Oddly, my aux negative disconnect and main battery ground seem to be the opposite of what's shown in the videos in the other ESS disable post. Thinking I might have missed a twist in the pairing without pulling everything out, I followed the instructions anyway for pulling that lead off after pulling the fuse and had no power to the Jeep. Do the techs actually have to clamp the terminal connectors on and did so in reverse or did they just attach them incorrectly? It just seems odd that the larger anchor blade terminal is attached to the smaller wire for the aux negative lead.

Edit: Pulled both leads off and reconnected the larger ground wire back. Works as described above. Pics added for reference.

 

[Shiner]

Glad I found this thread. Great find by the OP.

My question is... for those that intend to drive in this condition permanently.... will you eventually remove the AUX battery altogether with it no longer needed? Or is there a need (possibly obvious one) to keep it installed that I'm missing?

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